1. Field of the Invention
This invention relates to the field of adjustable and extendable torque bars of the type used for connecting driving tools to driven tools such as ratchet wrenches and sockets.
2. Prior Art
A torque bar or extension is a tool used to vary the distance between a driving tool, e.g., a ratchet or torque wrench and a driven tool, e.g., a socket. The first such extensions were of a fixed length necessitating the user to collect several of varied distances to accommodate a variety of situations. It became apparent that a need existed for a single extension that could be adjusted in length to provide a variety of lengths between a driving tool and a driven tool while still withstanding nominal torque forces. Many adjustable extensions have been proposed to accomplish this task. Most appear to be based upon the concept of a multi-sided tubular sleeve and a multi-sided rod telescopically positioned within the tubular sleeve. Variations in length were provided by threaded means, notches, etc. on the rod which mated with a locking mechanism carried by the tubular sleeve for positioning the telescoping rod at a fixed location vis-a-vis the tubular sleeve.
Several U.S. patents have been issued which illustrate adjustable extension bars. These include:
U.S. Pat. No. 3,306,639 discloses an extensible torque rod having a hexagonal rod telescopically engaged within a hexagonal shaped tube. A front end of the hexagonal rod is adapted for communication with a socket and the rear end of the hexagonal rod engages the front end of the hexagonal tube. The rear end of the tube is adapted for communication with a wrench. One side of the rod has a plurality of transverse and rounded grooves designed for engagement with a spring-pressed roller. In order to elongate or shorten the extension a collar is slid longitudinally with respect to the tube to release the spring-pressed roller and thereby disengage the roller from the groove thus "unlocking" the rod.
U.S. Pat. No. 4,960,015 discloses an adjustable torque rod comprising a rod telescopically mounted within a tubular shaped member. The rod carries a plurality of V shaped notches or teeth. Extension of the rod within the tubular member is controlled by a pawl supported by the tubular member which engages the V shaped notches. Like '639, this extensible bar utilizes a longitudinal slidable sleeve to release the pawl from engagement with the V shaped notches and thereby permit extension or contraction of the rod.
U.S. Pat. No. 4,317,393 discloses an extensible torque bar which utilizes an elongated rod having internal threads which engage with external threads associated with a sleeve. To elongate or retract the rod vis-a-vis the sleeve, the sleeve is rotated.
U.S. Pat. No. 5,033,337 discloses an extensible torque bar having circular indentations along a rod telescopically mounted within a tubular sleeve. A ball element is biased toward the circular indentations for maintaining the rod at a fixed location. A slidable pin is used to release the ball element. In another embodiment, the circular indentations extend around the periphery of an intermediate and extensible tube. The intermediate tube carries the rod thereby providing for multiple extensions within a single, adjustable torque rod.
Some problems noted with adjustable extension bars of the prior art are as follows:
1) most require one to unlock the extension in order to effect elongation and most are difficult to contract or extend;
2) substantial time is required to make adjustments from minimum to maximum lengths, and in addition, positioning and locking at new adjustments are assured only by sight or feel; and,
3) many do not have a provision for stopping the complete and undesirable disengagement of the telescopic rod from the elongated tube or sleeve;